Preliminary Results on Diet Composition of Swordfish, Xiphias gladius, Within the U.S. Florida Straits.

Despite the year-round abundance of swordfish in the Florida Straits and the hypothesized importance of this area as a nursery habitat, little is known about the diet composition or ecological role of swordfish in these waters. To address this gap in our knowledge of the trophic ecology of swordfish we plan to collect 150-200 stomachs over a full calendar year to study seasonal and ontogenetic changes in the diet. To date, 54 stomachs have been collected from different locations in the Florida Straits by commercial buoy and pelagic longline fishermen, swordfish tournaments throughout South Florida, and individual recreational swordfish anglers using rod-and-reel gear. Swordfish collected range in length from 53 cm to 196 cm, in weight from 28 kg to 109 kg. Preliminary results show that fish and cephalopods are the chief components of the diet. We expect to observe both seasonal and ontogenetic changes in diet composition reflective of shifting prey availability and trophic status of swordfish. Ultimately, determining seasonal and ontogenetic changes in diet will further our understanding of the ecological role of swordfish within the Florida Straits. As fisheries management increasingly becomes ecosystem-oriented this information is essential to managing both predator and prey.